Receiver for electromagnetic waves.



H0 MODEL.

wrrmssses: fifwwm i /ob 1 PATENTED MAY 5, 1903* R. A. FESSENDEN.

RECEIVER FOR ELECTROMAGNETIC WAVES.

APPLICATION FILED SEPT. 27, 1902.

FIGJ.

GIE VENTOE Att 'y- UNITED STATES PATENT OFFICE.

REGINALD A. FESSENDEN, OF PIT'ISBURG, PENNSYLVANIA.

RECEIVER FOR ELECTROMAGNETIC WAVES.

SPECIFICATION forming part of Letters Patent No. 727,327, dated May 5, .1903.

Application filed September 27, 1902. Serial No. 125,031. (No model.)

To all whom, it may concern:

Be it known that I, REGINALD A. Fnssnn- DEN, a citizen of the United States, residing at Pittsburg, in the county of Allegheny and fication.

The invention described herein relates to v certain improvements in receiving mechanisms for wireless signaling whereby the class or kind of receivers having imperfect contacts are rendered more efficient.

I have found that certain forms of imperfeet-contact receivers (more especially selfrestoring coherers consisting wholly or in part of carbon) require less energy to produce a signal when the number of contacts is reduced to a minimum, the best results being, attained when a single contact is used. I have found that when a minimum number of contacts'is used the imperfect contact may be "made to have such low resistance as not to absorb the energy of radiation at too rapid a rate to prevent resonance eflects-and that'hence such low-resistance imperfect contacts can be efficiently used in tuned circuits, constituting what may be called a current-operated, imperfect-contact receiver. I have alsofiound that the effectiveness of the coherer having a minimum of contacts is increased when used in conjunction with a step-down transformer, so that the energy received'by the receiving conductor is transformed into a greater current and less voltage than in the vertical conductor,

The invention is hereinafter more f ully described and'claimed. V

In the accompanying drawings, forming a part of this specification, Figure 1 is a view illustrative of one form of my improved receiving apparatus, and Fig. 2. illustrates a. modification thereof.

In the practice of my invention the primary 2 of a step-down transformer is arranged in operative relation to the receiving-conductor l, and the parts or members of the imperfect contact Aare' arranged in the circuit of the secondary 3 of the transformer and are also included in the signalingcircuit containing the indicating mechanism 4. The imperfect contact A is constructed to have a minimum number of contacts, preferably one, in series in the circuits, and the parts or members 5 andfi are both formed of carbon or carbonized structured material, such as carbonized velvet, or one of carbon and the other of metal arranged to be in contact with each oth'e'r, as shown. .A condenser 10 is arranged in the circuit of the secondary'of the transformer to preventthe shcrt-circuiting of the battery throughthe'secondary of thetransformer. It is preferred that the contacts havean appreciable surface, as shown in Figs. 1 and 2, so as to have low resistance. By low resistance is meant low as compared with the resistance of a coherer of the ordinary form. A suitable-resistance when used without transformer is one hundred to three hundred ohms and when used with step-down transformer, as shown in Fig. l, a resistance of thirty to one hundred ohms. The low resistance may also beobtainedby'pressure, as-shown in Fig. 2, where the weight of the arm 9 presses down the contact 5.

In lieu of the stationary blocks shown in Fig. l I may employ a disk 6, formed of carbon or metal, such as platinum or iridium,

. mounted on a spindle 7, driven by clockwork 8, and a roller 5*, loosely mounted on a supporting-arm 9, so as to bear upon the disk.

In operation the currents produced by the electromagnetic waves in the circuit containing the secondary of the transformer and the imperfect contact alter the resistance of the circuit containing the indicating mechanism.

1 claim herein as my invention 1. In a system of signaling-byelectromagnetic waves, the combination at the receivlug-station of a receiving-conductor, a stepdown transformer in operative relation to the conductor, ,two carbon bodies in contact with each other in series with the secondary of the transformer, and an indicating-circuit also ineluding said carbon bodies, substantially-as set forth.

'2. In a system of signaling by electromagnetic waves, the combination at the receiving-station of a receiving-conductor, a. stepdown transformer in operative relation to the. com] uctor,and a movable carbon nlate,'a roller formed of conducting material, said plate and roller being in series with the secondary of the transformer, and an indicating-circuit also including the plate and roller, substantially as set forth.

.3. In a. system of signaling by electromagnetic waves, at the receiving-station an imperfect-contact receiver, having one of its elements formed of a carbonized structured materialysubstantially as set forth.

In testimony whereof I have hereunto set my bani].

' REGINALD A. FESSENDEN.

Witnesses: F. E. GAITHER,

DARWIx S. W0L00TT. 

